The use of stacked steel lamina in the construction in electrical machines having rotor/stator elements has been found useful to reduce magnetic eddy current losses as the magnetic fields rise and fall within such machines. Laminated stators that are typically used in electric motors form the stationary exteriors of such motors and are provided with a plurality of slots and teeth on their inner surfaces upon which structure wire coils are wound and/or otherwise secured. To increase magnetic performance and reduce magnetic clogging, the teeth provided on such stators have widened faces or surface adjacent the rotor. By widening the faces or inner surfaces of the teeth, often only small slots between the teeth provide access to insert or wind the wire coils into the slots and around the teeth. The wire which is inserted into the slots and wound around the teeth form the electromagnetic coils of the motor. In addition to motors, alternators and generators have similar structures/construction. Because of the physical structural restrictions, the resulting coils do not have precise parallel wound turns and tend to have longer wire lengths (causing higher resistance) and lower copper density.
In high current electrical machines that require large cross sectional areas of wire or buss bars, inserting or winding a coil in a one piece stator slot can be difficult or even impossible, due to the small access slot opening and the stiffness of the conductor used.
U.S. Pat. No. 2,153,563 to Hubacker discloses a method of fabricating an electric motor that involves the use of a laminated stator having open slots and straight teeth which allow for easy coil winding. The straight teeth are capped by laminated steel tooth extensions that widen to a typical tooth width and slot size. The laminated tooth extensions taught by Hubacker are held by an inner ring and do not receive the coils. The tooth extensions serve only to transmit magnetic flux to the rotor and have tooth widths that are greater than the size of the coils' inside dimensions.
U.S. Pat. No. 4,912,353 to Kondo et al. discloses a two-piece motor stator construction that uses an inner ring and an outer ring. The inner ring is an annular structure having a plurality of stator teeth that extend radially outward from an outer surface thereof. The tip of each stator tooth includes a male dovetail structure. The male dovetail structure is larger than the portion of the tooth holding the coil. Accordingly, the construction prohibits the use of a bobbin or form wound coil. The wire coils in Kondo et al. are wound onto the teeth projecting from the inner annular ring. Thereafter, the male dovetail portions of teeth are pressed into complementary shaped female dovetail slots provided in the outer stator ring, thus forming a complete stator assembly.